feat: add search functionality

[bashbunni]

Description

It would add lots of value to be able to search a document for keywords. Similar to how we filter lists or use / in vim

Related Issues

https://github.com/charmbracelet/glow/issues/183

[bashbunni]

Based on our conversation internally, we likely want a pager bubble build on viewport that you could search. It would include an overlap between viewport bubble + status bar bubble. Glamour will remain a rendering lib, not something interactive.

Features

What we’ve been envisioning for the pager bubble is basically rebuilding the glow pager but without glamour rendering so it’s more flexible. so basically:

• [ ] viewport
• [ ] status bar
• [ ] toggle-able help

Bonus

• [ ] break off the status bar into it’s own bubble so it can be reused, but that could always happen later too
• [ ] glamour integration built in too (or maybe viewport has it baked in :thinking: ). So I could see two methods on the model like SetContent(string) and SetMarkdown(string)